1. Field of the Invention
This invention relates to a supply package of elastic yarns in the form of a double-face, two thread-system, warp-knit tape from which the elastic yarns can be unravelled. In particular, the invention concerns such a supply package which, because of its specific knit structure, is easy to unravel and split into narrower tapes.
2. Description of the Prior Art
U.S. Pat. No. 3,827,261 discloses an elastic-yarn supply package in the form of a flat, deknittable tape, which is produced on a warp-knitting machine, such as a Raschel machine, having two needle bars and two fully threaded guide bars. Nonknitted ends of the elastic yarns hang out of one end of the tape. Pulling on the nonknitted ends causes the knitted stitches of the tape to unravel (i.e., deknit). The thusly unravelled yarns then may be fed to a fabric-making machine or other textile operations, such as yarn covering, core spinning, and the like. Monofilament yarns, preferably of spandex polymer, are disclosed.
The elastic yarn supply package of U.S. Pat. No. 3,827,261 is a double-face, two thread-system, warp-knit tape. Adjacent wales of the tape are located such that one wale is on one face of the tape and the adjacent wale is on the other face of the tape. The yarns from every other wale on one face of the tape combine their loops in the intervening wale on the other face of the tape. Each needle stitch is formed of two yarns, one from each of the two thread systems, i.e., one from each of the two guide bars. Underlaps of the two thread system cross each other and run in opposite directions between adjacent wales. In conventional Raschel-machine lap notation, the disclosed construction can be designated as 2-4, 2-0/2-0, 2-4. Conventional lap notation, as given in D. F. Paling, Warp Knitting Technology, Columbine Press, Great Britain (1970) page 216, is used throughout the present application.
Elastic yarn supply packages of the above-described type have been used commercially. However, such packages have several shortcomings. In particular, the packages are difficult to split along wales. This lack of splittability can result in waste because the number of elastic yarns in the package usually does not correspond to the exact number of ends required for the variety of subsequent fabric-forming operations that may be desired. If a supply package could be split readily along wales, narrower tapes having the exact number of ends required for the next operation could be separated from the package and the remaining portion of the package could be saved for later or different uses, thereby avoiding waste.
The known supply package suffers additional shortcomings because of its particular stitch construction. This construction, which provides only two ends in each wale, limits the rates at which the packages can be produced. Furthermore, the supply packages are known only with heavy denier elastic threads. Applicant has found that if fine denier elastic threads are used with the warp-knit construction of the known packages, difficulties are encountered in dividing the unravelled wales into individual ends.
In view of the above, the purpose of this invention is to provide an elastic yarn supply package that is easier to split and deknit, has an increased number of ends per wale, and is capable of being manufactured efficiently and used satisfactorily with elastic filaments of fine denier.